I don't think it's categorically wrong to say something is too simple. There are accepted terms for that: over-simplification, simplistic. There's also the Ei

I don't think it's categorically wrong to say something is too simple. There are accepted terms for that: over-simplification, simplistic. There's also the Einstein line: "Everything should be made as simple as possible, but no simpler." I have no idea if PeerJS is actually too simple, but the "shape" of KaoruAoiShiho's statement seems fine.